l 答案及題目解析
Key:
1.B 2.A 3.C 4.C 5.A 6.B 7.D 8.D 9.B10.C 11.D 12.B 13-14.125
題目解析：
1. In paragraph 1, what does the author say about the presence of a blowhole in cetaceans?
（Factual Information Question）
A.It clearly indicates that cetaceans are mammals.
B.It cannot conceal the fact that cetaceans are mammals.
C.It is the main difference between cetaceans and land-dwelling mammals.
D.It cannot yield clues about the origins of cetaceans.
相關(guān)原句：
Their streamlined bodies, the absence of hind legs, and the presence of
a fluke and blowhole cannot disguise their affinities with land dwelling mammals.（Paragraph 1）
本題解析：
cannot disguise…意為“不能掩蓋…”，因此 “the presence of blowhole cannot disguise their affinities with land dwelling mammals”意思是“具有blowhol（出氣孔）并不能掩蓋這一事實：鯨類動物和陸棲哺乳動物有姻親關(guān)系（affinities）”；B選項中cannot concea（不能隱藏）l恰好與 cannot disguise相吻合，并指出鯨類動物是哺乳動物的事實，因此選擇B。
正確答案：
B
2. Which of the following can be inferred from paragraph 1 about early sea otters?（Inference Question）
A.It is not difficult to imagine what they looked like
B.There were great numbers of them.
C.They lived in the sea only.
D.They did not leave many fossil remains.
相關(guān)原句：
However, unlike the cases of sea otters and pinnipeds (seals, sea lions and walruses whose limbs are functional both on land and at sea),
it is not easy to envision what the first whales looked like. （Paragraph 1）
本題解析：
unlike意為“與…不同”，it is not easy to envision意為“不容易設(shè)想…”。本句為轉(zhuǎn)折，即“與海獺（sea otters）不同，人們很難想象最初鯨類的樣貌”，因此邏輯取非得出“sea otters的樣貌不難想象”，選擇A。
正確答案：
A
3. The word precious in the passage is closest in meaning to （Vocabulary Question）
A.Exact
B.Scarce
C.Valuable
D.Initial
相關(guān)原句：
Although limited to a skull, the Pakicetus fossil provides precious details on the origins of cetaceans.(Paragraph 3)
本題解析：
precious意為“珍貴的，有價值的”，后文種種由該化石得出的科研結(jié)論也表明P化石極有科學(xué)價值，與valuable同意。因此選擇C。
正確答案：
C
4. Pakicetus and modern cetaceans have similar（Factual Information Question）
A.Hearing structures
B.Adaptations for diving
C.Skull shapes
D.Breeding locations
相關(guān)原句：
The fossil consists of a complete skull of an archaeocyte, an extinct group of ancestors of modern cetaceans. (Paragraph 3)
本題解析：
根據(jù)原句得出P化石與現(xiàn)代鯨類的祖先(archaeocyte)擁有同樣的完整頭骨(a complete skull)，可推出P與現(xiàn)代鯨類頭骨應(yīng)該類似。因此選擇C。
此題亦可用排除法：
A. “The skull is cetacean-like but
its jawbones lack the enlarged space
that is filled with fat or oil and used for receiving underwater sound in modern whales. Pakicetus probably detected sound through the ear opening as in land mammals.”該句指出P化石的顎骨（jawbones）缺少鯨類動物擁有的由脂肪和油脂填充的擴充性空間（enlarged space
that is…），聽力構(gòu)造不同，并猜測它應(yīng)該通過耳孔(the ear opening)接受聲音，排除A。
B. “The skull also lacks a blowhole, another cetacean adaptation for diving.”該句明確指出P頭骨缺少出氣孔（blowhole），同鯨類潛水構(gòu)造不同，排除B。
D.It probably bred and gave birth on land.關(guān)于P在何處繁殖尚無定論，文章猜測（probably）在陸地（give birth on land），排除D。
正確答案：
C
5. The word it in the passage refers to（Reference Question）
A.Pakicetus
B.Fish
C.Life
D.ocean
相關(guān)原句：
It has been suggested that Pakicetus fed on fish in shallow water and was not yet adapted for life in the open ocean. It probably bred and gave birth on land. (Paragraph 3)
本題解析：
科學(xué)家猜測Pakicetus可能靠淺水區(qū)魚類為食并尚未適應(yīng)海洋生活，由此得出“很可能在陸地繁殖”的主體“it”正是指Pakicetus。因此選A。
正確答案：
A
6. The word exposed in the passage is closest in meaning to （Vocabulary Question）
A.Explained
B.Visible
C.Identified
D.Located
相關(guān)原句：
Basilosaurus, were found in sediments left by the Tethys Sea and now exposed in the Sahara desert.( Paragraph 4)
本題解析：
原句中“l(fā)eft by the Tethys Sea”修飾sediments（沉積物）,即B骨架發(fā)現(xiàn)于T海遺留的沉積物中；exposed則意為“暴露在”，相當(dāng)于uncovered，A skeleton that is uncovered can be seen, Visible就相當(dāng)于can be seen.
正確答案：
B
7. The hind leg of Basilosaurus was a significant find because it showed that Basilosaurus（Factual Information Question）
A.Lived later than Ambulocetus natans
B.Lived at the same time as Pakicetus
C.Was able to swim well
D.Could not have walked on land
相關(guān)原句：
Many incomplete skeletons were found but they included, for the first time in an archaeocyte, a complete hind leg that features a foot with three tiny toes. Such legs would have been far too small to have supported the 50-foot-long Basilosaurus on land. Basilosaurus was undoubtedly a fully marine whale with possibly nonfunctional, or vestigial, hind legs. ( Paragraph 4)
本題解析：
“Such legs would have been far too small to have supported the 50-foot-long Basilosaurus on land”，即B骨架的后肢太小以至于不能支撐其巨大身軀在陸地生活?！癇asilosaurus was undoubtedly a fully marine whale with possibly nonfunctional, or vestigial, hind legs.”文章接著指出，B絕對是完全的海洋生物，其后肢很可能已不再具有實用功能。因此，后肢（hind leg）之所以是重大發(fā)現(xiàn)正是因為它向人們表明Basilosaurus不可能生活在陸地且一定為海洋生物，選擇D。
注意C選項為迷惑選項，文章中 hind leg只說明Basilosaurus不能在陸地生活，并未說明它擅長游泳（swim well）；注意文中特別指出hind legs是possibly nonfunctional, or vestigial（退化的，發(fā)育不良的），所以它更不可能支持B游泳了。
正確答案：
D
8. It can be inferred that Basilosaurus bred and gave birth in which of the following locations（Inference Question）
A.On land
B.Both on land and at sea
C.In shallow water
D.In a marine environment
相關(guān)原句：
Basilosaurus was undoubtedly a fully marine whale with possibly nonfunctional, or vestigial, hind legs. ( Paragraph 4)
本題解析：
段落結(jié)尾已明確指出“Basilosaurus was undoubtedly a fully marine whale”（Basilosaurus是進化完全的海洋鯨類），因此B的一切活動都必然在海洋中，包括繁殖。選擇D。
正確答案：
D
9.Why does the author use the word luckily in mentioning that the Ambulocetus natans fossil included hind legs?
（Vocabulary Question）
A.Fossil legs of early whales are a rare find.
B.The legs provided important information about the evolution of cetaceans.
C.The discovery allowed scientists to reconstruct a complete skeleton of the whale.
D.Until that time, only the front legs of early whales had been discovered.
相關(guān)原句：
The fossil luckily includes a good portion of the hind legs. The legs were strong and ended in long feet very much like those of a modern pinniped. The legs were certainly functional both on land and at sea.（Paragraph 5）
本題解析：
luckily意為“幸運地”，稱其“幸運”是就A化石的科學(xué)價值而言：因為它具有a good portion of the hind leg(比例完整的后肢)，從而使科學(xué)家推出“The legs were certainly functional both on land and at sea”（A動物為水陸兩棲）。綜上，正是由于legs提供了重要的科學(xué)信息，人們才稱它luckily，因此選擇B。
正確答案：
B
10. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage?
（Sentence Simplification Question）
A.Even though Ambulocetus swam by moving its body up and down, it did not have a backbone.
B.The backbone of Ambulocetus, which allowed it to swim, provides evidence of its missing fluke.
C.Although Ambulocetus had no fluke, its backbone structure shows that it swam likemodern whales.
D.By moving the rear parts of their bodies up and down, modern whales swim in a different way from the way Ambulocetus swam.
相關(guān)原句：
The structure of the backbone shows, however, that Ambulocetus swam like modern whales by moving the rear portion of its body up and down, even though a fluke was missing. （Paragraph 5，highlighted sentence）
本題解析：
對此句理解應(yīng)結(jié)合其上一句“The whale retained a tail and lacked a fluke, the major means of locomotion in modern cetaceans”，該句指出A化石缺少了現(xiàn)代鯨類水中驅(qū)動的構(gòu)造fluke.接著本句“The structure of the backbone shows Ambulocetus swam like modern whales even though a fluke was missing”指出：“雖然缺少fluke，A化石的背骨結(jié)構(gòu)（the structure of the backbone）說明它正是像現(xiàn)代鯨類一樣游泳。因此選擇C。
正確答案：
C
11. The word propulsion in the passage is closest in meaning to（Vocabulary Question）
A.Staying afloat
B.Changing direction
C.Decreasing weight
D.Moving forward
相關(guān)原句：
The large hind legs were used for propulsion in water. （Paragraph 5）
本題解析：
propulsion意為“驅(qū)動”，文中指Ambulocetus natans在水中向前游動，從前一句中“Ambulocetus swam like modern whales”也可推斷propulsion與 swim相關(guān)，應(yīng)為“向前游動”，因此選擇D。
正確答案：
D
12. Look at the four squares [■] that indicate where the following sentence can be added to the passage.
（Insert Text Question）
This is a question that has puzzled scientists for ages.
Where would the sentence best fit?
Extinct but already fully marine cetaceans are known from the fossil record. ■（A）How was the gap between a walking mammal and a swimming whale bridged? ■（B）This is a question that has puzzled scientists for ages. Missing until recently were fossils clearly intermediate, or transitional, between land mammals and cetaceans. ■(C)Very exciting discoveries have finally allowed scientists to reconstruct the most likely origins of cetaceans.■（D）In 1979, a team looking for fossils in northern Pakistan found what proved to be the oldest fossil whale.（Paragraph 1）
本題解析：
插入句中“this is a question”可以推出該句之前應(yīng)恰好提出了問題，而B處之前“How was the gap between a walking mammal and a swimming whale bridged? ”正與插入句相呼應(yīng)，因此選擇B。
正確答案：
B
13-14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some answer choices do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
（Prose Summary Question）
This passage discusses fossils that help to explain the likely origins of cetaceanswhales, porpoises, and dolphins.
●
●
●
Answer Choices
1. Recent discoveries of fossils have helped to show the link between land mammals and cetaceans.
2. The discovery of Ambulocetus natans provided evidence for a whale that lived both on land and at sea.
3. The skeleton of Basilosaurus was found in what had been the Tethys Sea, an area rich in fossil evidence.
4. Pakicetus is the oldest fossil whale yet to be found.
5. Fossils thought to be transitional forms between walking mammals and swimming whales were found.
6. Ambulocetus' hind legs were used for propulsion in the water.
本題解析：
正確答案應(yīng)陳述文章主要內(nèi)容----由三大化石的發(fā)現(xiàn)所得出的關(guān)于陸地哺乳動物與鯨類間進化的結(jié)論。
1選項“近期化石發(fā)現(xiàn)幫助科學(xué)家推斷陸生哺乳動物與鯨類的聯(lián)系”。文章正是討論三大化石發(fā)現(xiàn)如何幫助科學(xué)研究者推斷兩種物種的進化，因此1正確；
2選項“Ambulocetus natans化石是水陸兩棲的過渡階段鯨類”。文章最后一段描述了A化石不僅“具有很完好的后肢：強壯并且足部很長----水陸都可適應(yīng)”（The legs were strong and ended in long feet very much like those of a modern pinniped. The legs were certainly functional both on land and at sea），而且“其背骨結(jié)構(gòu)說明即使沒有fluke它仍像現(xiàn)代鯨類一樣游泳，后肢就用來在水中驅(qū)動身體”（ The large hind legs were used for propulsion in water；同時猜測它可能在陸地繁殖，陸地運動時可能類似現(xiàn)代海獅（On land, where it probably bred and gave birth, Ambulocetus may have moved around very much like a modern sea lion）；最后得出結(jié)論“Ambulocetus natans毫無疑問正是陸地哺乳動物到鯨類過渡中的海陸兩棲動物”（It was undoubtedly a whale that linked life on land with life at sea）。因此2正確；
3選項“Basilosaurus化石發(fā)現(xiàn)于T海，此處富含化石”，此為細節(jié)信息，不屬于總結(jié)內(nèi)容，況且B事實上發(fā)現(xiàn)于T海遺留的沉積物（sediments）中，并不是T海中；同時雖然文中三個化石都發(fā)現(xiàn)于T海周邊地區(qū)，但并沒有科學(xué)證據(jù)證明T海富含化石，選項錯誤；
4選項“P化石是最古老的鯨類化石”，屬于細節(jié)信息，與文章主要內(nèi)容無關(guān)，錯誤；
5選項“處于陸生哺乳動物和鯨類過渡階段的化石被發(fā)現(xiàn)”，即指Ambulocetus natans化石，正確；
6“A化石的后肢用于水中驅(qū)動”，屬于細節(jié)信息，與文章主要內(nèi)容無關(guān)，錯誤。
因此選擇125。
正確答案：
1，2，5
l 段意及難句解析：
●第一段：
段意：
本段指出鯨類動物（cetaceans）與陸棲哺乳動物有著密切聯(lián)系，目前已經(jīng)找到了能夠明確展示兩類動物是如何進化的化石。
難句分析：
1. Their streamlined bodies, the absence of hind legs, and the presence of a fluke and blowhole cannot disguise their affinities with land dwelling mammals.
短語：cannot disguise their affinities with：不能掩蓋它們與…的姻親關(guān)系
land dwelling mammals：陸棲哺乳動物
釋義：鯨類動物的流線型身體，后肢的缺少，三角狀尾鰭的存在以及頭頂?shù)某鰵饪祝ㄒ陨隙际堑湫偷暮Ｑ髣游锾攸c）并不能掩蓋它們與陸棲哺乳動物的姻親關(guān)系。
2. However, unlike the cases of sea otters and pinnipeds (seals, sea lions, and walruses, whose limbs are functional both on land and at sea), it is not easy to envision
what the first whales looked like.
短語：unlike the case of:與…的情況不同
it is not easy to envision:很難想象…的樣子
釋義：與海獺和其他鰭足動物不同，人們很難想象最初鯨類的模樣。邏輯轉(zhuǎn)換：人們很難想象最初鯨類動物的模樣，但與之相反，設(shè)想海獺等動物的原始樣貌應(yīng)較為容易。
3. How was the
gap between a walking mammal and a swimming whale bridged?
釋義：本段主旨句，提出文章所討論的中心問題：從陸棲哺乳動物到水生鯨類之間到底是如何進化的？
●第二段&第三段
段意：
兩段共描述了第一具重要考古發(fā)現(xiàn)：化石Pakicefus。段2敘述了化石P的發(fā)現(xiàn)地點和歷史年代，段3則詳細描述其特征并做出推論。關(guān)于化石P我們可得出以下信息：
1）發(fā)現(xiàn)于：1979年巴基斯坦北部，最古老的鯨類化石
2）三個事實：1.有一個完全的鯨類始祖A動物的skull(頭骨)
2. jawbones（顎骨）缺少鯨類動物擁有的由脂肪和油脂填充的擴充性空間
3.頭骨缺少blowhole
3）三個猜測：1.可能和陸棲動物一樣通過耳孔來接受聲音
2.可能（suggested）靠淺水區(qū)魚類為食，但尚未適應(yīng)海洋生活
3.可能在陸地繁殖
4）結(jié)論：P為陸棲動物M到現(xiàn)代鯨類的過渡（a transitional form）
難句分析：
1. Pakicetus was found embedded in rocks formed from river deposits that were 52 million years old.
分句：“formed from river deposits that were 52 million years old”：形成于距今52 million年前的河流沉積物中，修飾rocks
釋義：化石P被發(fā)現(xiàn)鑲嵌在巖石中，該巖石從距今52 million年前的河流沉積物中演化而來。
2. The fossil consists of a complete skull of an archaeocyte, an extinct group of ancestors of modern cetaceans.
短語：a complete skull：完整的頭骨
分句：“an extinct group of ancestors of modern cetaceans”修飾archaeocyte,即archaeocyte是鯨類動物的一種已滅絕的祖先
釋義：此句為事實1，化石P具有一個完整的鯨類始祖archaeocyte的頭骨。
3. The skull is cetacean-like but its jawbones lack the enlarged space that is filled with fat or oil and used for receiving underwater sound in modern whales.
分句：“that is filled with fat or oil and used for receiving underwater sound in modern whales”部分修飾enlarged space
釋義：化石P的顎骨（jawbones）缺少現(xiàn)代鯨類具有的擴大性空間，這部分空間通常由脂肪和油脂填充并用來收聽水下聲音。此句為事實2。
4. Pakicetus probably detected sound through the ear opening as in land mammals.
釋義：注意probably,此句為猜測1，化石P可能和陸棲動物一樣通過耳孔來接受聲音。
5. The skull also lacks a blowhole, another cetacean adaptation for diving.
釋義：此句為事實3，P頭骨缺少氣孔，該氣孔是鯨類適應(yīng)潛水活動的結(jié)構(gòu)。
6. Other features, however, show experts that Pakicetus is a transitional form between a group of extinct flesh-eating mammals, the mesonychids, and cetaceans.
分句： “a group of extinct flesh-eating mammals”修飾“the mesonychid”，即M動物是一類已滅絕的食肉哺乳動物
主干：Pakicetus is a transitional form between the mesonychids and cetaceans
釋義：此句指明化石P正是食肉哺乳動物M與鯨類的過渡階段形態(tài)，為本段結(jié)論。
7. It has been suggested that Pakicetus fed on fish in shallow water and was not yet adapted for life in the open ocean.
短語：fed on fish：以魚為食
shallow water：淺水區(qū)
釋義：注意suggested,此句為猜測2，即化石P可能生前靠淺水區(qū)魚類為食并尚未適應(yīng)海洋生活。
8. It probably bred and gave birth on land.
釋義：“it”指代化石P，此句為猜測3，指出Pakicetus可能在陸地繁殖。
●第四段：
段意：
本段描述第二具考古發(fā)現(xiàn)：Basilosaurus的骨架。關(guān)于Basilosaurus骨架我們可得出以下信息：
1）發(fā)現(xiàn)于1989年埃及
2）事實：1.生活于40 million年前，比化石P晚12 million年
2.首次具有完整的后肢，包括一只腳和三個腳趾
3）結(jié)論：Basilosaurus絕對已是完全的海洋鯨類。
難句分析：
1. Several skeletons of another early whale, Basilosaurus, were found in sediments left by the Tethys Sea and now exposed in the Sahara desert.
詞匯：exposed意為“暴露在”，此處指“處于，位于”。
分句：“l(fā)eft by the Tethys Sea”修飾sediments,即B骨架發(fā)現(xiàn)于T海遺留的沉積物中
釋義：人們在Tethys海遺留的沉積物中發(fā)現(xiàn)了若干Basilosaurus的骨架，這些骨架現(xiàn)在位于撒哈拉沙漠中。
2. This whale lived around 40 million years ago, 12 million years after Pakicefus.
釋義：此句為事實1，即Basilosaurus生活于40 million年前，比化石P晚12 million年。
3. Many incomplete skeletons were found but they included, for the first time in an archaeocyte, a complete hind leg that features a foot with three tiny toes.
分句：“a complete hind leg that features a foot with three tiny toes”即B具有完全的后肢，包括包括一只腳和三個腳趾
釋義： 此句為事實2。注意archaeocyte是鯨類動物的一種已滅絕的祖先（已在上段中指出），由此可知原始鯨類Basilosaurus也是archaeocyte進化過程中的階段性形態(tài)。
4.Such legs would have been far too small to have supported the 50-foot-long Basilosaurus on land. Basilosaurus was undoubtedly a fully marine whale with possibly nonfunctional, or vestigial, hind legs.
短語：“nonfunctional, or vestigial, hind legs”：無實用作用的，退化了的后肢。
分句：“would have been too small to have supported the 50-foot-long Basilosaurus on land”:（這后肢）太小以至于不可能支撐50英尺長的Basilosaurus在陸地活動
釋義：此句為本段結(jié)論，即Basilosaurus絕對已是（undoubtedly）完全的海洋鯨類。
●第五段：
段意：
本段描述第三具考古發(fā)現(xiàn)：化石Ambulocetus natans。關(guān)于化石A我們可得出以下信息：
1）發(fā)現(xiàn)于1994年巴基斯坦
2）事實：1.生活于49 million年前，晚于Pakicetus但早于Basilosaurus。三者順序為：P—A—B
2.具有很完好的后肢：強壯并且足部很長----水陸都可適應(yīng)
3.保留了尾巴但缺少三角狀,然而其背骨結(jié)構(gòu)說明即使沒有尾鰭它仍像現(xiàn)代鯨類一樣游泳，后肢就用來在水中驅(qū)動身體。
3）猜測：可能在陸地繁殖，陸地運動時可能類似現(xiàn)代海獅
4）結(jié)論：Ambulocetus natans毫無疑問正是陸地哺乳動物到鯨類過渡中的海陸兩棲動物。
rear：后方的
難句分析：
1. The now extinct whale Ambulocetus natans
lived in the Tethys Sea 49 million years ago. It lived around 3 million years after Pakicetus but 9 million before Basilosaurus.
主干：Ambulocetus natans lived after Pakicetus but before Basilosaurus
釋義：此句為事實1。指出Ambulocetus natans生活于49million年前的Tethys海中，它晚于Pakicetus 3million 年，但早于Basilosaurus 9 million年。
2.The fossil luckily includes a good portion of the hind legs. The legs were strong and ended in long feet very much like those of a modern pinniped. The legs were certainly functional both on land and at sea.
短語：a good portion of:很完好的一部分
be ended in：末端是…
分句：“ended in long feet very much like those of a modern pinniped”：實際為“ended in long feet (which is)very much like those of a modern pinniped”,修飾long feet
釋義：此處為事實2。A化石具有完好的后肢，后肢很強壯且足部很長，如同現(xiàn)代鰭足動物（如海獅）一樣，能夠同時在陸地和海洋活動。
3. The structure of the backbone shows, however, that Ambulocetus swam like modern whales by moving the rear portion of its body up and down, even though a fluke was missing.
分句：“the major means of locomotion in modern cetaceans”修飾fluke,即現(xiàn)代鯨類在水中前進時所依靠的是其三角狀尾鰭
主干：the structure of the backbone shows that Ambulocetus swam like modern whales
釋義：此處為事實3。說明A化石缺少三角狀尾鰭，但既便如此它仍能像現(xiàn)代鯨類一樣游泳。
4. On land, where it probably bred and gave birth, Ambulocetus may have moved around very much like a modern sea lion.
釋義：注意probably和may,此為猜測，即Ambulocetus可能在陸地繁殖后代，并且它在陸地運動時類似現(xiàn)代海獅。
5. It was undoubtedly a whale that linked life on land with life at sea.
釋義：此句為本段結(jié)論，即通過上文描述A兼具海洋動物和陸地哺乳動物的特點得出它毫無疑問正是陸地哺乳動物到海洋鯨類過渡過程中的海陸兩棲動物。
Key:
1.B 2.A 3.C 4.C 5.A 6.B 7.D 8.D 9.B10.C 11.D 12.B 13-14.125
題目解析：
1. In paragraph 1, what does the author say about the presence of a blowhole in cetaceans?
（Factual Information Question）
A.It clearly indicates that cetaceans are mammals.
B.It cannot conceal the fact that cetaceans are mammals.
C.It is the main difference between cetaceans and land-dwelling mammals.
D.It cannot yield clues about the origins of cetaceans.
相關(guān)原句：
Their streamlined bodies, the absence of hind legs, and the presence of
a fluke and blowhole cannot disguise their affinities with land dwelling mammals.（Paragraph 1）
本題解析：
cannot disguise…意為“不能掩蓋…”，因此 “the presence of blowhole cannot disguise their affinities with land dwelling mammals”意思是“具有blowhol（出氣孔）并不能掩蓋這一事實：鯨類動物和陸棲哺乳動物有姻親關(guān)系（affinities）”；B選項中cannot concea（不能隱藏）l恰好與 cannot disguise相吻合，并指出鯨類動物是哺乳動物的事實，因此選擇B。
正確答案：
B
2. Which of the following can be inferred from paragraph 1 about early sea otters?（Inference Question）
A.It is not difficult to imagine what they looked like
B.There were great numbers of them.
C.They lived in the sea only.
D.They did not leave many fossil remains.
相關(guān)原句：
However, unlike the cases of sea otters and pinnipeds (seals, sea lions and walruses whose limbs are functional both on land and at sea),
it is not easy to envision what the first whales looked like. （Paragraph 1）
本題解析：
unlike意為“與…不同”，it is not easy to envision意為“不容易設(shè)想…”。本句為轉(zhuǎn)折，即“與海獺（sea otters）不同，人們很難想象最初鯨類的樣貌”，因此邏輯取非得出“sea otters的樣貌不難想象”，選擇A。
正確答案：
A
3. The word precious in the passage is closest in meaning to （Vocabulary Question）
A.Exact
B.Scarce
C.Valuable
D.Initial
相關(guān)原句：
Although limited to a skull, the Pakicetus fossil provides precious details on the origins of cetaceans.(Paragraph 3)
本題解析：
precious意為“珍貴的，有價值的”，后文種種由該化石得出的科研結(jié)論也表明P化石極有科學(xué)價值，與valuable同意。因此選擇C。
正確答案：
C
4. Pakicetus and modern cetaceans have similar（Factual Information Question）
A.Hearing structures
B.Adaptations for diving
C.Skull shapes
D.Breeding locations
相關(guān)原句：
The fossil consists of a complete skull of an archaeocyte, an extinct group of ancestors of modern cetaceans. (Paragraph 3)
本題解析：
根據(jù)原句得出P化石與現(xiàn)代鯨類的祖先(archaeocyte)擁有同樣的完整頭骨(a complete skull)，可推出P與現(xiàn)代鯨類頭骨應(yīng)該類似。因此選擇C。
此題亦可用排除法：
A. “The skull is cetacean-like but
its jawbones lack the enlarged space
that is filled with fat or oil and used for receiving underwater sound in modern whales. Pakicetus probably detected sound through the ear opening as in land mammals.”該句指出P化石的顎骨（jawbones）缺少鯨類動物擁有的由脂肪和油脂填充的擴充性空間（enlarged space
that is…），聽力構(gòu)造不同，并猜測它應(yīng)該通過耳孔(the ear opening)接受聲音，排除A。
B. “The skull also lacks a blowhole, another cetacean adaptation for diving.”該句明確指出P頭骨缺少出氣孔（blowhole），同鯨類潛水構(gòu)造不同，排除B。
D.It probably bred and gave birth on land.關(guān)于P在何處繁殖尚無定論，文章猜測（probably）在陸地（give birth on land），排除D。
正確答案：
C
5. The word it in the passage refers to（Reference Question）
A.Pakicetus
B.Fish
C.Life
D.ocean
相關(guān)原句：
It has been suggested that Pakicetus fed on fish in shallow water and was not yet adapted for life in the open ocean. It probably bred and gave birth on land. (Paragraph 3)
本題解析：
科學(xué)家猜測Pakicetus可能靠淺水區(qū)魚類為食并尚未適應(yīng)海洋生活，由此得出“很可能在陸地繁殖”的主體“it”正是指Pakicetus。因此選A。
正確答案：
A
6. The word exposed in the passage is closest in meaning to （Vocabulary Question）
A.Explained
B.Visible
C.Identified
D.Located
相關(guān)原句：
Basilosaurus, were found in sediments left by the Tethys Sea and now exposed in the Sahara desert.( Paragraph 4)
本題解析：
原句中“l(fā)eft by the Tethys Sea”修飾sediments（沉積物）,即B骨架發(fā)現(xiàn)于T海遺留的沉積物中；exposed則意為“暴露在”，相當(dāng)于uncovered，A skeleton that is uncovered can be seen, Visible就相當(dāng)于can be seen.
正確答案：
B
7. The hind leg of Basilosaurus was a significant find because it showed that Basilosaurus（Factual Information Question）
A.Lived later than Ambulocetus natans
B.Lived at the same time as Pakicetus
C.Was able to swim well
D.Could not have walked on land
相關(guān)原句：
Many incomplete skeletons were found but they included, for the first time in an archaeocyte, a complete hind leg that features a foot with three tiny toes. Such legs would have been far too small to have supported the 50-foot-long Basilosaurus on land. Basilosaurus was undoubtedly a fully marine whale with possibly nonfunctional, or vestigial, hind legs. ( Paragraph 4)
本題解析：
“Such legs would have been far too small to have supported the 50-foot-long Basilosaurus on land”，即B骨架的后肢太小以至于不能支撐其巨大身軀在陸地生活?！癇asilosaurus was undoubtedly a fully marine whale with possibly nonfunctional, or vestigial, hind legs.”文章接著指出，B絕對是完全的海洋生物，其后肢很可能已不再具有實用功能。因此，后肢（hind leg）之所以是重大發(fā)現(xiàn)正是因為它向人們表明Basilosaurus不可能生活在陸地且一定為海洋生物，選擇D。
注意C選項為迷惑選項，文章中 hind leg只說明Basilosaurus不能在陸地生活，并未說明它擅長游泳（swim well）；注意文中特別指出hind legs是possibly nonfunctional, or vestigial（退化的，發(fā)育不良的），所以它更不可能支持B游泳了。
正確答案：
D
8. It can be inferred that Basilosaurus bred and gave birth in which of the following locations（Inference Question）
A.On land
B.Both on land and at sea
C.In shallow water
D.In a marine environment
相關(guān)原句：
Basilosaurus was undoubtedly a fully marine whale with possibly nonfunctional, or vestigial, hind legs. ( Paragraph 4)
本題解析：
段落結(jié)尾已明確指出“Basilosaurus was undoubtedly a fully marine whale”（Basilosaurus是進化完全的海洋鯨類），因此B的一切活動都必然在海洋中，包括繁殖。選擇D。
正確答案：
D
9.Why does the author use the word luckily in mentioning that the Ambulocetus natans fossil included hind legs?
（Vocabulary Question）
A.Fossil legs of early whales are a rare find.
B.The legs provided important information about the evolution of cetaceans.
C.The discovery allowed scientists to reconstruct a complete skeleton of the whale.
D.Until that time, only the front legs of early whales had been discovered.
相關(guān)原句：
The fossil luckily includes a good portion of the hind legs. The legs were strong and ended in long feet very much like those of a modern pinniped. The legs were certainly functional both on land and at sea.（Paragraph 5）
本題解析：
luckily意為“幸運地”，稱其“幸運”是就A化石的科學(xué)價值而言：因為它具有a good portion of the hind leg(比例完整的后肢)，從而使科學(xué)家推出“The legs were certainly functional both on land and at sea”（A動物為水陸兩棲）。綜上，正是由于legs提供了重要的科學(xué)信息，人們才稱它luckily，因此選擇B。
正確答案：
B
10. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage?
（Sentence Simplification Question）
A.Even though Ambulocetus swam by moving its body up and down, it did not have a backbone.
B.The backbone of Ambulocetus, which allowed it to swim, provides evidence of its missing fluke.
C.Although Ambulocetus had no fluke, its backbone structure shows that it swam likemodern whales.
D.By moving the rear parts of their bodies up and down, modern whales swim in a different way from the way Ambulocetus swam.
相關(guān)原句：
The structure of the backbone shows, however, that Ambulocetus swam like modern whales by moving the rear portion of its body up and down, even though a fluke was missing. （Paragraph 5，highlighted sentence）
本題解析：
對此句理解應(yīng)結(jié)合其上一句“The whale retained a tail and lacked a fluke, the major means of locomotion in modern cetaceans”，該句指出A化石缺少了現(xiàn)代鯨類水中驅(qū)動的構(gòu)造fluke.接著本句“The structure of the backbone shows Ambulocetus swam like modern whales even though a fluke was missing”指出：“雖然缺少fluke，A化石的背骨結(jié)構(gòu)（the structure of the backbone）說明它正是像現(xiàn)代鯨類一樣游泳。因此選擇C。
正確答案：
C
11. The word propulsion in the passage is closest in meaning to（Vocabulary Question）
A.Staying afloat
B.Changing direction
C.Decreasing weight
D.Moving forward
相關(guān)原句：
The large hind legs were used for propulsion in water. （Paragraph 5）
本題解析：
propulsion意為“驅(qū)動”，文中指Ambulocetus natans在水中向前游動，從前一句中“Ambulocetus swam like modern whales”也可推斷propulsion與 swim相關(guān)，應(yīng)為“向前游動”，因此選擇D。
正確答案：
D
12. Look at the four squares [■] that indicate where the following sentence can be added to the passage.
（Insert Text Question）
This is a question that has puzzled scientists for ages.
Where would the sentence best fit?
Extinct but already fully marine cetaceans are known from the fossil record. ■（A）How was the gap between a walking mammal and a swimming whale bridged? ■（B）This is a question that has puzzled scientists for ages. Missing until recently were fossils clearly intermediate, or transitional, between land mammals and cetaceans. ■(C)Very exciting discoveries have finally allowed scientists to reconstruct the most likely origins of cetaceans.■（D）In 1979, a team looking for fossils in northern Pakistan found what proved to be the oldest fossil whale.（Paragraph 1）
本題解析：
插入句中“this is a question”可以推出該句之前應(yīng)恰好提出了問題，而B處之前“How was the gap between a walking mammal and a swimming whale bridged? ”正與插入句相呼應(yīng)，因此選擇B。
正確答案：
B
13-14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some answer choices do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
（Prose Summary Question）
This passage discusses fossils that help to explain the likely origins of cetaceanswhales, porpoises, and dolphins.
●
●
●
Answer Choices
1. Recent discoveries of fossils have helped to show the link between land mammals and cetaceans.
2. The discovery of Ambulocetus natans provided evidence for a whale that lived both on land and at sea.
3. The skeleton of Basilosaurus was found in what had been the Tethys Sea, an area rich in fossil evidence.
4. Pakicetus is the oldest fossil whale yet to be found.
5. Fossils thought to be transitional forms between walking mammals and swimming whales were found.
6. Ambulocetus' hind legs were used for propulsion in the water.
本題解析：
正確答案應(yīng)陳述文章主要內(nèi)容----由三大化石的發(fā)現(xiàn)所得出的關(guān)于陸地哺乳動物與鯨類間進化的結(jié)論。
1選項“近期化石發(fā)現(xiàn)幫助科學(xué)家推斷陸生哺乳動物與鯨類的聯(lián)系”。文章正是討論三大化石發(fā)現(xiàn)如何幫助科學(xué)研究者推斷兩種物種的進化，因此1正確；
2選項“Ambulocetus natans化石是水陸兩棲的過渡階段鯨類”。文章最后一段描述了A化石不僅“具有很完好的后肢：強壯并且足部很長----水陸都可適應(yīng)”（The legs were strong and ended in long feet very much like those of a modern pinniped. The legs were certainly functional both on land and at sea），而且“其背骨結(jié)構(gòu)說明即使沒有fluke它仍像現(xiàn)代鯨類一樣游泳，后肢就用來在水中驅(qū)動身體”（ The large hind legs were used for propulsion in water；同時猜測它可能在陸地繁殖，陸地運動時可能類似現(xiàn)代海獅（On land, where it probably bred and gave birth, Ambulocetus may have moved around very much like a modern sea lion）；最后得出結(jié)論“Ambulocetus natans毫無疑問正是陸地哺乳動物到鯨類過渡中的海陸兩棲動物”（It was undoubtedly a whale that linked life on land with life at sea）。因此2正確；
3選項“Basilosaurus化石發(fā)現(xiàn)于T海，此處富含化石”，此為細節(jié)信息，不屬于總結(jié)內(nèi)容，況且B事實上發(fā)現(xiàn)于T海遺留的沉積物（sediments）中，并不是T海中；同時雖然文中三個化石都發(fā)現(xiàn)于T海周邊地區(qū)，但并沒有科學(xué)證據(jù)證明T海富含化石，選項錯誤；
4選項“P化石是最古老的鯨類化石”，屬于細節(jié)信息，與文章主要內(nèi)容無關(guān)，錯誤；
5選項“處于陸生哺乳動物和鯨類過渡階段的化石被發(fā)現(xiàn)”，即指Ambulocetus natans化石，正確；
6“A化石的后肢用于水中驅(qū)動”，屬于細節(jié)信息，與文章主要內(nèi)容無關(guān)，錯誤。
因此選擇125。
正確答案：
1，2，5
l 段意及難句解析：
●第一段：
段意：
本段指出鯨類動物（cetaceans）與陸棲哺乳動物有著密切聯(lián)系，目前已經(jīng)找到了能夠明確展示兩類動物是如何進化的化石。
難句分析：
1. Their streamlined bodies, the absence of hind legs, and the presence of a fluke and blowhole cannot disguise their affinities with land dwelling mammals.
短語：cannot disguise their affinities with：不能掩蓋它們與…的姻親關(guān)系
land dwelling mammals：陸棲哺乳動物
釋義：鯨類動物的流線型身體，后肢的缺少，三角狀尾鰭的存在以及頭頂?shù)某鰵饪祝ㄒ陨隙际堑湫偷暮Ｑ髣游锾攸c）并不能掩蓋它們與陸棲哺乳動物的姻親關(guān)系。
2. However, unlike the cases of sea otters and pinnipeds (seals, sea lions, and walruses, whose limbs are functional both on land and at sea), it is not easy to envision
what the first whales looked like.
短語：unlike the case of:與…的情況不同
it is not easy to envision:很難想象…的樣子
釋義：與海獺和其他鰭足動物不同，人們很難想象最初鯨類的模樣。邏輯轉(zhuǎn)換：人們很難想象最初鯨類動物的模樣，但與之相反，設(shè)想海獺等動物的原始樣貌應(yīng)較為容易。
3. How was the
gap between a walking mammal and a swimming whale bridged?
釋義：本段主旨句，提出文章所討論的中心問題：從陸棲哺乳動物到水生鯨類之間到底是如何進化的？
●第二段&第三段
段意：
兩段共描述了第一具重要考古發(fā)現(xiàn)：化石Pakicefus。段2敘述了化石P的發(fā)現(xiàn)地點和歷史年代，段3則詳細描述其特征并做出推論。關(guān)于化石P我們可得出以下信息：
1）發(fā)現(xiàn)于：1979年巴基斯坦北部，最古老的鯨類化石
2）三個事實：1.有一個完全的鯨類始祖A動物的skull(頭骨)
2. jawbones（顎骨）缺少鯨類動物擁有的由脂肪和油脂填充的擴充性空間
3.頭骨缺少blowhole
3）三個猜測：1.可能和陸棲動物一樣通過耳孔來接受聲音
2.可能（suggested）靠淺水區(qū)魚類為食，但尚未適應(yīng)海洋生活
3.可能在陸地繁殖
4）結(jié)論：P為陸棲動物M到現(xiàn)代鯨類的過渡（a transitional form）
難句分析：
1. Pakicetus was found embedded in rocks formed from river deposits that were 52 million years old.
分句：“formed from river deposits that were 52 million years old”：形成于距今52 million年前的河流沉積物中，修飾rocks
釋義：化石P被發(fā)現(xiàn)鑲嵌在巖石中，該巖石從距今52 million年前的河流沉積物中演化而來。
2. The fossil consists of a complete skull of an archaeocyte, an extinct group of ancestors of modern cetaceans.
短語：a complete skull：完整的頭骨
分句：“an extinct group of ancestors of modern cetaceans”修飾archaeocyte,即archaeocyte是鯨類動物的一種已滅絕的祖先
釋義：此句為事實1，化石P具有一個完整的鯨類始祖archaeocyte的頭骨。
3. The skull is cetacean-like but its jawbones lack the enlarged space that is filled with fat or oil and used for receiving underwater sound in modern whales.
分句：“that is filled with fat or oil and used for receiving underwater sound in modern whales”部分修飾enlarged space
釋義：化石P的顎骨（jawbones）缺少現(xiàn)代鯨類具有的擴大性空間，這部分空間通常由脂肪和油脂填充并用來收聽水下聲音。此句為事實2。
4. Pakicetus probably detected sound through the ear opening as in land mammals.
釋義：注意probably,此句為猜測1，化石P可能和陸棲動物一樣通過耳孔來接受聲音。
5. The skull also lacks a blowhole, another cetacean adaptation for diving.
釋義：此句為事實3，P頭骨缺少氣孔，該氣孔是鯨類適應(yīng)潛水活動的結(jié)構(gòu)。
6. Other features, however, show experts that Pakicetus is a transitional form between a group of extinct flesh-eating mammals, the mesonychids, and cetaceans.
分句： “a group of extinct flesh-eating mammals”修飾“the mesonychid”，即M動物是一類已滅絕的食肉哺乳動物
主干：Pakicetus is a transitional form between the mesonychids and cetaceans
釋義：此句指明化石P正是食肉哺乳動物M與鯨類的過渡階段形態(tài)，為本段結(jié)論。
7. It has been suggested that Pakicetus fed on fish in shallow water and was not yet adapted for life in the open ocean.
短語：fed on fish：以魚為食
shallow water：淺水區(qū)
釋義：注意suggested,此句為猜測2，即化石P可能生前靠淺水區(qū)魚類為食并尚未適應(yīng)海洋生活。
8. It probably bred and gave birth on land.
釋義：“it”指代化石P，此句為猜測3，指出Pakicetus可能在陸地繁殖。
●第四段：
段意：
本段描述第二具考古發(fā)現(xiàn)：Basilosaurus的骨架。關(guān)于Basilosaurus骨架我們可得出以下信息：
1）發(fā)現(xiàn)于1989年埃及
2）事實：1.生活于40 million年前，比化石P晚12 million年
2.首次具有完整的后肢，包括一只腳和三個腳趾
3）結(jié)論：Basilosaurus絕對已是完全的海洋鯨類。
難句分析：
1. Several skeletons of another early whale, Basilosaurus, were found in sediments left by the Tethys Sea and now exposed in the Sahara desert.
詞匯：exposed意為“暴露在”，此處指“處于，位于”。
分句：“l(fā)eft by the Tethys Sea”修飾sediments,即B骨架發(fā)現(xiàn)于T海遺留的沉積物中
釋義：人們在Tethys海遺留的沉積物中發(fā)現(xiàn)了若干Basilosaurus的骨架，這些骨架現(xiàn)在位于撒哈拉沙漠中。
2. This whale lived around 40 million years ago, 12 million years after Pakicefus.
釋義：此句為事實1，即Basilosaurus生活于40 million年前，比化石P晚12 million年。
3. Many incomplete skeletons were found but they included, for the first time in an archaeocyte, a complete hind leg that features a foot with three tiny toes.
分句：“a complete hind leg that features a foot with three tiny toes”即B具有完全的后肢，包括包括一只腳和三個腳趾
釋義： 此句為事實2。注意archaeocyte是鯨類動物的一種已滅絕的祖先（已在上段中指出），由此可知原始鯨類Basilosaurus也是archaeocyte進化過程中的階段性形態(tài)。
4.Such legs would have been far too small to have supported the 50-foot-long Basilosaurus on land. Basilosaurus was undoubtedly a fully marine whale with possibly nonfunctional, or vestigial, hind legs.
短語：“nonfunctional, or vestigial, hind legs”：無實用作用的，退化了的后肢。
分句：“would have been too small to have supported the 50-foot-long Basilosaurus on land”:（這后肢）太小以至于不可能支撐50英尺長的Basilosaurus在陸地活動
釋義：此句為本段結(jié)論，即Basilosaurus絕對已是（undoubtedly）完全的海洋鯨類。
●第五段：
段意：
本段描述第三具考古發(fā)現(xiàn)：化石Ambulocetus natans。關(guān)于化石A我們可得出以下信息：
1）發(fā)現(xiàn)于1994年巴基斯坦
2）事實：1.生活于49 million年前，晚于Pakicetus但早于Basilosaurus。三者順序為：P—A—B
2.具有很完好的后肢：強壯并且足部很長----水陸都可適應(yīng)
3.保留了尾巴但缺少三角狀,然而其背骨結(jié)構(gòu)說明即使沒有尾鰭它仍像現(xiàn)代鯨類一樣游泳，后肢就用來在水中驅(qū)動身體。
3）猜測：可能在陸地繁殖，陸地運動時可能類似現(xiàn)代海獅
4）結(jié)論：Ambulocetus natans毫無疑問正是陸地哺乳動物到鯨類過渡中的海陸兩棲動物。
rear：后方的
難句分析：
1. The now extinct whale Ambulocetus natans
lived in the Tethys Sea 49 million years ago. It lived around 3 million years after Pakicetus but 9 million before Basilosaurus.
主干：Ambulocetus natans lived after Pakicetus but before Basilosaurus
釋義：此句為事實1。指出Ambulocetus natans生活于49million年前的Tethys海中，它晚于Pakicetus 3million 年，但早于Basilosaurus 9 million年。
2.The fossil luckily includes a good portion of the hind legs. The legs were strong and ended in long feet very much like those of a modern pinniped. The legs were certainly functional both on land and at sea.
短語：a good portion of:很完好的一部分
be ended in：末端是…
分句：“ended in long feet very much like those of a modern pinniped”：實際為“ended in long feet (which is)very much like those of a modern pinniped”,修飾long feet
釋義：此處為事實2。A化石具有完好的后肢，后肢很強壯且足部很長，如同現(xiàn)代鰭足動物（如海獅）一樣，能夠同時在陸地和海洋活動。
3. The structure of the backbone shows, however, that Ambulocetus swam like modern whales by moving the rear portion of its body up and down, even though a fluke was missing.
分句：“the major means of locomotion in modern cetaceans”修飾fluke,即現(xiàn)代鯨類在水中前進時所依靠的是其三角狀尾鰭
主干：the structure of the backbone shows that Ambulocetus swam like modern whales
釋義：此處為事實3。說明A化石缺少三角狀尾鰭，但既便如此它仍能像現(xiàn)代鯨類一樣游泳。
4. On land, where it probably bred and gave birth, Ambulocetus may have moved around very much like a modern sea lion.
釋義：注意probably和may,此為猜測，即Ambulocetus可能在陸地繁殖后代，并且它在陸地運動時類似現(xiàn)代海獅。
5. It was undoubtedly a whale that linked life on land with life at sea.
釋義：此句為本段結(jié)論，即通過上文描述A兼具海洋動物和陸地哺乳動物的特點得出它毫無疑問正是陸地哺乳動物到海洋鯨類過渡過程中的海陸兩棲動物。